/Engine/Source/Runtime/CoreUObject/Public/UObject/LinkerLoad.h
Before loading anything objects off disk, this function can be used to discover the object in memory. This could happen in the editor when you save a package (which destroys the linker) and then play PIE, which would cause the Linker to be recreated. However, the objects are still in memory, so there is no need to reload them.
The object that was found, or NULL if it wasn't found
[UObject](API\Runtime\CoreUObject\UObject\UObject) * FindExistingExport ( int32 ExportIndex )